Conventional couplings or electrical connection devices are generally constituted by metal sleeves or rings which are intended to be engaged on two electrically conductive zones for interconnection and to perform both mechanical and electrical interconnection thereof. Frequently, said mechanical and electrical interconnection are provided by means of a sleeve which is deformed or crimped. Crimping permanently deforms the sleeve to a considerable extent, and, generally speaking, couplings of this type can usually be used once only since the considerable sleeve deformation which occurs during crimping prevents the initial properties of elasticity and malleability of the sleeve from being subsequently reused.
However, recent work in this field has made use of materials having shape memory, thereby enabling this type of equipment to be re-used several times in succession. For example, proposals have been made to make a coupling sleeve, or at least a portion thereof, in a material having shape memory, i.e. a material capable of giving the sleeve the property of occupying to different shapes depending on the temperature of the sleeve relative to a transition temperature of the material from which it is made. These two shapes correspond to an expanded shape for the sleeve in which electrical and mechanical interconnection of the contact zones is not ensured and a retracted or non-expanded state of the sleeve in which both electrical and mechanical connection of the contact zones are, indeed, provided.
Couplings of this type are described, in particular, in European patent application published under the No. 0 112 618, and in Research Disclosure Publication No. 212, December 1981, page 442, abstract No. 21237, published in Havant Hampshire, GB in an article entitled "Method of attaching coiled leads to electrodes or electrode pins".
However, the types of coupling described in the above-specified documents necessarily require a mechanical force or stress to be applied externally to the sleeve in order to return it adequately to its expanded condition over a plurality of connection-disconnection cycles, said force or stress being capable of returning the sleeve to its expanded shape state and of returning the conductive zones to a state in which mechanical and electrical interconnection is absent.
Consequently, and in particular concerning couplings of the type described in above-mentioned European patent application No. 0 112 618, a resilient element or auxiliary spring in the form of a split metal ring concentric with the sleeve and in contact therewith is provided in order to ensure a re-usable connection function for substantially all types of conductive zone which are compatible with the size of the sleeve-spring assembly. With reference to the above-specified Research Disclosure, the coupling is constituted by a simple sleeve which can only be used in the presence of conductive zones for interconnection which are capable of exerting an external force suitable for returning a sleeve to its expanded state. As shown in the drawing of said publication, this type of coupling can only be used repetitively if one of the conductive zones possesses radial elasticity relative to the sleeve and is constituted by a spring or a coil.
Preferred embodiments of the present invention remedy the above drawbacks by implementing an electrical coupling capable of being re-used many times, without requiring any auxiliary resilient or spring system.
Preferred embodiments of the present invention also provide an electrical coupling suitable for being mounted to provide electrical connection after the corresponding conductive contact zones have been wired up.